System

Definition

A system is the part of the universe being studied, isolated for observation and measurement. In thermochemistry, it refers to the specific set of reactants and products involved in a reaction.

5 Must Know Facts For Your Next Test

1. A system can be open, closed, or isolated depending on its interaction with surroundings.
2. In an open system, both energy and matter can be exchanged with the surroundings.
3. In a closed system, only energy can be exchanged with the surroundings; matter remains constant.
4. In an isolated system, neither energy nor matter is exchanged with the surroundings.
5. The choice of system affects how energy changes are measured and analyzed in calorimetry.

Review Questions

• What distinguishes an open system from a closed one?
• Why is it important to define the boundaries of a system in thermochemistry?
• How does an isolated system differ from other types of systems?

Related terms

Surroundings: Everything external to the system that can exchange energy or matter with it.

Calorimetry: The science of measuring heat changes in chemical reactions or physical processes.

Enthalpy: A thermodynamic quantity representing the total heat content of a system at constant pressure.